Refactor language detection logic to allow non-static CLD data sources.

chrome/browser/component_updater/cld_component_installer.cc

Index: chrome/browser/component_updater/cld_component_installer.cc
diff --git a/chrome/browser/component_updater/cld_component_installer.cc b/chrome/browser/component_updater/cld_component_installer.cc
index a761ee6988175c3479f5dc2b5d5f4c5eff7bda11..90090763fed9f3329572805c9f327ef511fd076d 100644
--- a/chrome/browser/component_updater/cld_component_installer.cc
+++ b/chrome/browser/component_updater/cld_component_installer.cc
@@ -15,6 +15,7 @@
 #include "base/path_service.h"
 #include "components/component_updater/component_updater_paths.h"
 #include "components/translate/content/browser/browser_cld_data_provider.h"
+#include "components/translate/content/browser/browser_cld_data_provider_factory.h"
 #include "components/translate/content/common/cld_data_source.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/ssl/ssl_config_service.h"
@@ -108,10 +109,11 @@ std::string CldComponentInstallerTraits::GetName() const {
 
 void RegisterCldComponent(ComponentUpdateService* cus) {
   // Make sure we don't start up if the CLD data source isn't compatible.
-  if (!translate::CldDataSource::ShouldRegisterForComponentUpdates()) {
+  if (translate::CldDataSource::Get() !=
+      translate::CldDataSource::GetComponentDataSource()) {

[Takashi Toyoshima, 2014/11/06 14:34:28]

Can you have a browser test that can detect this serious configuration error?
That will be useful to protect your code from unexpected changes by other
developers who just does a cleanup or something. Build file does not need a
strict review, and developers often think it's ok if all tries pass the build.

I have a sad experience that my feature was unexpectedly disabled by another
developer's change for build configuration. TODO is ok.

[Andrew Hayden (chromium.org), 2014/11/10 14:06:35]

Sadly, there's not a way to have a test for this because the high-level test
targets themselves have to configure which data source they need. This should
now be near-impossible, though, since the code that invokes RegisterCldComponent
now does a specific "if it's the CLD component, call RegisterCldComponent" (see
chrome_browser_main.cc, line 427 in this patchset).

Looking at this again, though, we can make things better. The reason for
chrome_browser_main.cc to make the decision on whether or not to call this
method was to avoid adding the Component Updater code when it wasn't necessary
to build; but I've abandoned that approach because of its unnecessary
complexity, so we could just move this check right inside RegisterCldComponent
and call it unconditionally. I'll do that, and then this will be clearer.

[Takashi Toyoshima, 2014/11/11 07:16:36]

OK, it sounds reasonable.

     // This is a serious build-time configuration error.
     LOG(ERROR) << "Wrong CLD data source: " <<
-        translate::CldDataSource::GetName();
+        translate::CldDataSource::Get()->GetName();
     NOTREACHED();
     return;
   }
@@ -132,7 +134,7 @@ void CldComponentInstallerTraits::SetLatestCldDataFile(
     const base::FilePath& path) {
   VLOG(1) << "Setting CLD data file location: " << path.value();
   g_latest_cld_data_file.Get() = path;
-  translate::SetCldDataFilePath(path);
+  translate::CldDataSource::Get()->SetCldDataFilePath(path);
 }
 
 base::FilePath CldComponentInstallerTraits::GetLatestCldDataFile() {